Mural television screen



Aug. 21, 1956 P. M. G. TOULON 2,760,119

MURAL TELEVISION SCREEN Filed Jan. 15, @952 I V 5 Sheets-Sheet 1 INVENTOR WERRE 1- G'. Tat/ o ATTORNEYS a BY IM ff f Aug. 21, 1956 P. M. G. TOULON 2,760,119

MURAL TELEVISION SCREEN Filed Jan. 15, 1952 5 Shee ts-Sheet 2 r -1 l5 cww/rroL i I his 2/ ar INVENTOR Q5212: M 6 75am BY 74M ATTORNEY5 Aug. 21, 1956 P. M. 5. TOULON 2,760,119

MURAL TELEVISION SCREEN Filed Jan. 15, 1952 5 Sheets-Sheet 3 l l I CENTER OF acfiEE/V 725m 1% G. 7.1M, H64. Y

ATTOR NE Y5 Aug. 21, 1956 P. M. s. TOULON 2,760,119

MURAL TELEVISION SCREEN Filed Jan. 15, 1952 5 Sheets-Sheet 4 INVENTOR M G. 'FfluLoN ATTORNEYJ Aug. 21, 1956 P. M. G. TOULON 2,760,119

MURAL TELEVISION SCREEN Filed Jan. 15, 1952 5 Sheets-Sheet 5 INVENTOR ST/ 522? M G. 001-00 ATTORNEY:

:AlL TELEVESION SQREEN Application January 15, 1952, Serial No. 266,514

14 (:laims. (Cl. 315-169) This invention relates to television tubes and more particularly, to the construction of a mural television tube, whereby the viewing surface of such a tube may be increased without the usual corresponding increase in bulk and depth of the tube.

At the present time, the tubes widely used for television reception are of the well known cathode ray type. These tubes constitute, essentially, a viewing screen, an electron gun, and control electrodes, disposed within a single evacuated glass shell. The forward face of this glass shell is coated, on its inner surface, with a phosphorescent material, which is activated by the impact of an electron beam originating at the electron gun. The television picture is formed by a process of sweeping the beam across the phosphorescent surface and modulating the beam while exploring the surface through the medium of the control electrodes, as is well known in the prior art.

In order for the cathode ray beam to be effective over the entire phosphorescent viewing surface, tube construction must be such that the electron gun is removed from the screen a distance approximating the average dimension of that screen. This factor presents a serious limitation to the size of the viewing surface for, although careful design has effected some savings, as the size of the screen becomes progressively larger, the necessary increase in the depth of the cathode ray tube soon makes the bulk of the tube too large for practicability.

The conventional cathode ray tube in television has serious limitations systems for the production of large pictures on the tube face itself. Other systems, however, are known in which the video intelligence is distributed over the entire surface of a phosphorescent screen. Such systems have been particularly described in United States Patents 2,201,066 and 2,471,253 to P. M. G. Toulon. The former patent discloses a system employing reflected light used with an optical viewing surface, while the latter describes a distribution system to be used with modulated cell complexes.

It is an object of the present invention to provide a mural television tube which employs the principle of distributing video intelligence over the entire surface of a phosphorescent viewing screen without the use of a cathode ray tube. However, it will be understood that charged particle control features forming subcombinations of the present invention may be used with a cathode ray tube and such use falls within the ambit of the present invention.

It is a further purpose of this invention to provide a mural television surface, the viewing area of which is not limited by considerations of the increasing third dimension of television tubes which normally accompanies an increase in size of the viewing screen. In promoting these two objects, the usual concentrated source of an electron beam, the conventional electron gun placed a considerable distance from the viewing screen, is preferably dispensed with, and the screen is instead supported in an ionized gas, proper gating means atent being provided for the passage of ions to the phosphorescent material.

It is a further object of this invention to provide a practical method of construction of a mural television tube having a viewing screen limited in size only by the strength of the materials employed in an atmosphere of ionized gas. In this respect, the dimensions of the tube need not be limited by its thickness which may be kept at a minimum compatible with resistance to atmospheric pressure. Furthermore this construction provides means of resisting atmospheric pressure which are distinct from the viewing screen itself. Again gas filled tubes at atmospheric pressure may be used.

Another object of this invention is to provide a composite tube in which the phosphorescent screen is substantially plane, the phosphorescent material itself being placed on the screen in a discontinuous deposit. Where desired a lenticular surface is provided, as will be described, to effect an appearance of continuity of deposit to an observer.

A still further object of this invention is to provide a tube of large surface readily adaptable to color television, as well as to three dimensional television.

These and further objects will be readily seen from the following description and correlative drawings in which like numerals refer to like elements.

Fig. l is a perspective view of the mural tube placed in a frame, in accordance with the invention.

Fig. 2 is a vertical section of the composite tube, and the frame therefor,

Fig. 3 is a partial vertical section along a center line of Fig. 1 showing the internal structure of the invention.

Fig. 4 is a schematic light-line diagram illustrating the construction, operation and optical effect of the lenticular surface of the viewing screen in one embodiment of the invention.

Fig. 5 is a perspective diagram illustrating the curvature and configuration of the front outer face of the tube,

Figs. 6A, 6B, and 6C represent possible modifications of the tube container construction and sealing means employed therein.

Fig. 7 is a fragmentary perspective section of one form of internal structure of the invention illustrating one possible method of construction of said tube and internal structure, and

Fig. 8 is a front elevation of the internal structure of the modified form of the tube, showing the internal configuration of anodes, cathodes, and supporting members.

Figs. 9A, 9B, 9C and 9D show a detail of construction which is particularly effective for color television.

Fig. 1 shows one form of a television receiver 10, incorporating the mural television tube having a glass face 11 appearing through an opening in frame 12.

As shown in Figure 2, the tube is composed of an external container, and an internal viewing screen supported therein. The tube container has an oblong transparent front section 11, made of a material such as glass, and a complementary rear section 14 sealed by seal 20 to the front section 11 along the periphery of the tube. The rear section 14 is ordinarily made of a metallic material, with openings such as 15 around which are sealed receptacles 17 arranged to receive a plurality of electrical connections. The number of openings 15 in the rear section 14 of the container may be one, two, or more, depending upon the number of electrical connections required for the proper operation of the tube, and the number of electrical connections which a typical receptacle 17 may be designed to accommodate.

The front surface 11 of the container, in the form shown in Fig. 2 is, designed to withstand atmospheric pressure. It will ordinarily be formed of structural glass, and may include pre stressed metal elements to increase its rigidity. The actual surface of section 11 may be a composite curved surface of constant curve changes, or a composite of two curvatures, a curvature A along the horizontal sweep of the surface, and a curvature l3 along the vertical sweep, as illustrated in Figure 5.

The front surface 11 is sealed by seal 20 to rear section 14 in the typical container for the viewing screen. For ease of construction and strength of container structure it is preferable to form the rear section 14 cf metal. However, it has also been found practicable to construct the rear section of structural glass as at 140 in Figure 6C, to form an all glass tube. Further modifications in the construction of the rear surface of the tube container are illustrated in Figures 6A and 6B. In Figure 6A, rear section 140 is of metal. However, in this modification, rather than have the rear section 1451 present a. continuous metallic curve as in section 14, section 14a is a reverse cantilever surface provided with stiffening corrugation 16. This method of constructing the rear surface of the tube container produces an even flatter tube than is obtained in the previously iliustrated glass-metal or glass-glass tubes. In the form shown in Fig. 6B the front section 11 of the container is sealed to metallic section 219, which is itself in turn sealed to rear section 14b, a structural glass section, provided, of course, with the aforementioned outlets for electrical connections.

The front and rear sections of the tube container are joined along their adjacent complementary peripheries by seals 20. The seals used in the construction of the container may be permanent. They may also be of the well known pull-apart enamel type. In this latter case the base of the seal should be a mixture of lead and silica in proportions determined by the temperature which the seal must withstand in the degassing of the tube. Further, if the seal is of the pull-apart type, it should allow to be broken at a temperature somewhat higher than the aforementioned temperature, in order that the screen elements, to be described, supported within the container may be repaired when and as needed.

The one or more openings 15 to be found in the rear section 14 of the container provide for the passage of electrical connections from one or more plugs 17 to the exterior of the tube container. The plugs 17 are sealed across the openings 15, and will ordinarily be of glass construction. In a plug having a diameter of two and one half inches it has been found practicable to connect as many as two hundred fifty wires. The actual number of openings 15 will therefore depend on the number of connections necessary for the proper operation of the tube. As methods of gating and as the number of standard lines or dots per line of viewing screen are changed, a simple change in design of the number of plugs to be used in the tube readily adapts the tube exterior to these changes and adapts the tube to any standard which may be set.

The exterior of the plugs 17 are of the standard construction and may be of the Jones type if desired. The tube shown in Figure 2 can be placed in a receiver frame 12 of very shallow depth. The frame 12 may be formed of standard materials such as wood or plastic. The control circuits 21 for amplification and distribution may be located Within frame 12 by incorporating miniature tubes, the external adjustment of these circuits 21 being readily accomplished by control knobs 13. The various leads from the receiver control circuits may be sealed, exterior to the circuits proper, into one or more receptacles 22 complementary to the plugs 17 and forming the other half of a Jones plug.

A further modification of receiver design incorporating this invention is one in which the control circuits are placed in a cabinet exterior to the picture tube. In such a design the tube could be placed in a frame suitable for the support thereof, and positioned on a wall surface. A

cabinet containing the control circuits may be located on the floor below the tube frame, or at some distance from the tube frame, with a lead connecting the two distinct portions of the receiver. Proper design of the receiver shown in Figure 2 would allow the entire receiver to be positioned on a wall surface or on a table top.

The mural tube container is preferably of oblong configuration, and is formed to two basic external sections. The front and rear sections of the container are so curved that a cavit is formed in the container interior. Sup- .p 23 fastened to the rear section 14 mount a phosphorescent screen 255 within said cavity. The cavity of the visible screen contains a rarificd gaseous atmosphere 3%, of mercury vapor, helium, xenon, or like gases having low ionization'time characteristics. his .rnosphere is maintained in a state of ionized g on called plasma by means of an anode and one or several cathodes disposed within the tube container will be described.

The basic components of the screen 25 are a transparent front plate 3i, control electrodes and 33. and a grid structure 3 3-, such as honeycombs. Grid pre ses the control electrodes 3?. and 33 against the whole surface of the plate 31.

The forward surface of trans -ent plate 31 may be flat, as shown in Figure 2 in part1: section at 310. The rear surface of plate 31 is divided, by corrugations 35 into five hundred twenty-five horizontal lines, this number of lines being used to correspond to present standards of transmission. The actual number of lines may, of course, be readily changed by appropriate manufacture to the number of divisions adopted for such other standards of transmission as may from time to time be adopted.

Conductive fluorescent materials are deposited on the rear face of plate 31 along the divisions 35 to form targets 36. Electrical connections to these target materials 36 permit them to receive a voltage, at recurring intervals. of sufficient magnitude to allow a periodic flow of ions to the targets 36 from plasma 30, activating the targets to cause an issue of visible light through transparent facing 31.

The control electrodes 3.. and are mounted immediately to the rear of transparent plate 31. The electrodes are physically placed orthogonally to one another, electrode 32 being vertical, ant. electrode being horizontal. An auxiliary discussion of the pattern of depositing the phosphorescent material will make the purpose of this configuration apparent.

As stated above, the rear surface of screen 31 is divided into five hundred twenty-five horizontal lines or into any other division which may be adopted for standard transmission, and conductive fluorescent material 36 is deposited along each of these lines. Each of the horizontal lines is composed of five hundred dots, and, if desired, the rear of screen 31 may be so formed as to pro vide an individual depressed area for each dot rather than having the fluorescent material deposited .in a plurality of continuous lines. The five hundred twenty-five lines of screen 31 are explored, as in the cathode ray tube, in a line interlace fashion of two fields per picture, or in any other interlace system of line or dot interlace. The sequency of exploration of these lines is effected at the field frequency, a relatively low frequency which requires through proper compounding about thirty outlets.

The cross picture scanning is made through a high speed distribution system working an individual outlet for each of the five hundred dots which compose a line. Each of the five-hundred dots of each line is also on a predetermined vertical line, each horizontally scanned line having a definite ordinate intercept. Therefore each of the five hundred vertical lines has associated with it a vertical control electrode 32 and each of these vertical lines is conductively connected to one of five hundred terminals. Each of the five hundred twenty-five horizontal lines, of course, has a horizontal electrode 33 associated with it, these to the rear horizontal lines also being connected to appropriate terminals.

The multiplex system of high speed distribution of video intelligence at dot frequency within the five hundred vertical lines is well known in the art. The preferred and most compact system of high speed pulse distribution has been described in U. S. Patent 2,471,253, said patent referring to phase shifted gating signals at dot frequency which activate in turn the various five hundred dots along a horizontal line. Such a system of distribution is preferred in the operation of the mural tube herein disclosed, although other systems accomplishing the same results may be adapted.

As the foregoing discussion shows, the cross-hatch or grid-like configuration of horizontal and vertical electrodes 33 and 32 placed immediately behind the screen 31 regulates for each point of screen the quantity of ions which are allowed to reach fluorescent layers 36. Each point of the screen corresponding to a distinct video signal is controlled by the crossing of a vertical electrode 32 and a horizontal electrode 33. These electrodes are preferably layers of conductive maerials deposited on sheet support 37 of insulating material, and are preferably covered with an insulating coating 38. Apertures 39 are formed by aligned perforations through the insulating materials 37 and 38;, and through each cross location of the vertical and horizontal electrodes. This construction provides an aperture 39 corresponding to each dot or target 36 of fluorescent material on screen 31 to cause the flow of ions, at the proper time, to that dot.

The control electrodes 32 and 33 are pressed against the Whole surface of the screen 31 by a grid structure 34, such as honey-combs. The construction of means 34 is such as to allow the plasma to circulate freely within the various combs. Therefore honey-comb 34 may be used to serve the dual purpose of providing support for the control electrodes and acting as the operating anode in the ionization of atmosphere 30. Accordingly, anode 34 is constructed of metal or of other conductive material having sufficient structural strength to support the gating electrodes 32, 33 and the plate 31. A typical anode 34 is formed of a nickel honeycomb, having wall sections of approximately .020 inch in thickness. Anode 34 is connected to a source of potential of constant value and operates in a manner well known in the art to ionize the gaseous atmosphere 38 which may be suitably rarefied to cause charged molecules to be effective. The ionized particles here referred to may be thought of as negatively or positively charged and the control voltages adjusted accordingly. Where the envelope section 11 is sufficiently strong to withstand the reduced pressure electrons may be employed to excite targets 36. These may require higher potentials so that the electrons can attain sufficient veloc ity. T his anode potential may be ground potential if desirable in light of the other potentials being used. The potential applied to fluorescent targets 36 is of a varying magnitude, always positive to the anode potential and increasing so at periodic intervals. Such a varying potential may be of the well known sawtooth waveform having a suitable peak value, the least magnitude of this sawtooth potential being substantially equal to the fixed potential applied to anode 34. In this Way, ions Will tend to flow toward the fluorescent targets 36, rather than to the anode 34, at periods of time determined by the repetition rate of the saw'tooth, this flow being controlled or gated by electrodes 32 and 33. Vertical modulating electrodes 32 carry video intelligence signals from the video distributor which has .its channel terminals connected to the terminals of all the vertical electrodes 32, as described in my U. S. Patent No. 2,471,253. Although the intersections of control electrodes 32, 33 are shown as corresponding to Cartesian coordinate it will be understood that polar coordinates may be employed. For special applications logarithmic oblique or other mathematical coordinates may be used.

The structural function of supporting anode 34 is illustrated in part in Figure 3, which shows, to a greatly enlarged scale, the inter-relationship of the various parts of the visible screen elements. Means 34, which is vertical for the most part, has horizontal arm members 34a at each extremity, each member 34a having a vertical projection or lug 34b. The design of the supporting anode means 34 and of the transparent plate 31 is such that vertical sections 34b extend under screen 31 in supporting relation. Sections 34b may further be provided with set screws 40 to hold the anode 34 and the screen 31 in fixed relation, at the same time supporting control electrodes 32 and 33 between them. Set screws 40 may be loosened making the various elements of the screen 25 accessible for repairs in the event that seals 20 need ever be broken for that purpose.

A preferred configuration of electrode and supporting means is illustrated in Fig. 8. As shown in that figure, the supporting means 81 may be constructed of a plurality of horizontal and vertical rods or strip members, suitably interlocked with one another as illustrated in Figure 7, instead of the honeycomb construction 34 previously described. Means 81 is preferably constructed of metal for the required structural strength. However as the supporting means 81 and suede means 82 are separate structures in this embodiment, supporting means 81 may be constructed of any material having sufiicient strength. Such materials may very Well be of an insulating nature, of plastic, glass, or fiber, if desired and the cross members 81 moulded as a grid in one piece.

As has already been indicated, the theory of operation of the tube utilizes the instant response of a gas maintained in a continual state of ionization. Such an ionization is accomplished, as is well known in the prior art, by electrodes, anodes and cathodes, maintained at proper potentials. The cathode is at a potential negative to that of the anode, and a proper choice of potentials will permit sufficient current to pass through the gaseous medium to maintain the ionized state. In the preferred embodiment of anode and cathode disposition, illustrated in Figure 7, the ionization anode 82 may comprise two congruent sections fastened to the supporting structure 81 at its outer extremities. Anode 82 is best constructed of a thin sheet of metallic material. If the overall tube dimensioning, configuration, and design is such that the anode 82 is not required to carry high current for extended periods of time, the anode 82 may well be fashioned by painted circuit technique, the anode consisting of an insulating backing on which has been deposited, by spraying or painting, a thin coating of conductive material in the desired configuration. Other methods of construction, such as electroplating of the anode 82 may of course be used. Electrical conductors connect the anode 82 to proper voltage sources and allow the desired constant potential to be applied to said anode.

The cathode or cathodes 83 required to complete the ionization network may be disposed within the tube in one of several ways. Such a cathode is symbolically represented as 41 in Fig. 3. Preferred methods of locating the cathodes 83 may be seen in Figure 8. The cathodes 83 may be provided as a single continuous structure, or may, in case of construction in larger tubes, comprise a plurality of electrodes, each maintained at the same potential negative to the anode 82. The cathodes 83 will ordinarily be located forward of the vertical members of supporting means 81 and intermediate to anode 82 sections. If desired, however, the actual disposition of cathodes 83 and anode 82 may be interior or anterior to the supporting means 81, such variations being readily effected through proper design. Leads 84 are connected to cathodes 83 to supply the required potentials to said cathodes.

In the event that cathode 83 is of a single continuous construction, disposed between the anode 82 sections along the vertical dimension of the tube interior, the edges of anode 82 adjacent to cathode 83 may be of a single unbroken configuration, represented as 82/1. However, if a plurality of cathodes 83 is used. it has been found that such a cathode construction will not provide a constant state of ionization throughout plasma 353*. To overcome this deleterious effect, it has been further found that, should the plurality of cathode construction be used, the anode sections 82 should assume the configuration illustrated in Figure 8. Such a configuration of short and long conductive members comprising the anode will tend to counteract the nonconstant ionization effect of discontinuous cathodes 83.

As may be readily seen from the foregoing discussion of ionization electrode configuration and disposition. the paths of ionization will tend to be parallel to the face of the tube (in the plane of Figure 8). At periodic in.- tervals, as a result of the varying potential applied to conductive fluorescent targets 36, ions will flow to targets 36 in paths perpendicular to the paths of ionization (perpendicular to the plane of Figure 8).

The preceding disclosure of supporting structure 81 will be seen to lend itself to a modified form of tube construction, shown in Figure 7. In this type of tube, the external container, disclosed in Figures 2 and 6, is dispensed with. Basically, however, the configuration of the tube is the same, the tube consisting of a structural glass forward surface 74 and an anterior metal plate 71 fashioned so as completely to contain the interior elements of the tube, and sealed to the forward surface by seals 20, of the type previously disclosed. In this embodiment of the invention, the rear surface of forward plate 74 is not corrugated, and a continuous layer of fluorescent material 72 is deposited thereon.

The control electrodes found within the tube include horizontal electrodes 33 and vertical electrodes 32 of conductive material, disposed on opposite sides of a perforated insulating sheet 37. The control electrodes 32, 33 are covered, in turn, by further insulating layers 38a and 38b, in much the same manner as has already been disclosed. Apertures 39 extend through the control electrodes 32, 33 and insulating sheets 38, 38a and 38b for the passage of ions to fluorescent deposit 72, at the crossing points of respective vertical and horizontal electrodes 32 and 33. There is, of course, an aperture 39 corresponding to each dot element to be located on material 72. Insulating sheet 38!) may be corrugated or channeled corresponding to corrugations 35 located along the rear surface of plate 31 in Fig. 3. There is, in this embodiment, a single corrugation for each line of video intelligence to be represented, and apertures 39, representing the dot elements of a given line, are recessed along the corrugations. The composite control electrode surface is supported at its upper and lower extremities by supporting members 75, the latter being fastened to rear metal surface 71 by any desired means, such as spot welds 73.

To the rear of the control electrode assembly 32, 33 are to be found the supporting members 81, anode 82, cathode 33, as well as plasma 30, previously discussed. As may be seen from Fig. 7, the horizontal members of supporting structure 81 project forward and have hemmed edges 81a which impinge upon the insulating sheet 38a, providing lateral support therefor. The vertical members of grid structure 81 act as spacers for the horizontal members, the overall configuration thus supporting the interior structure of the tube while simultaneously providing structural strength to member 71 in the resistance of atmospheric pressure.

In general, as has been previously described, the forward surface of transparent plate 31 may be planar, as illustrated at 31a in Fig. 2. Where the fluorescent material 36 is applied to the rear surface of screen 31 in a discontinuous deposit, a series of black spaces between the many line or dot elements of the screen may be apparent to an observer. In a preferred embodiment of the invention, shown in Figs. 3 and 7, the forward surface of screen 31 is of lenticular or multi-plano-convcx construction. Under such a construction the black space effect will disappear completely.

In fashioning the forward surface of screen 31 in this lenticular construction, the pitch between each lens element is taken as equal to the distance between centers of adjacent phosphorescent lines or layers 36. Further, each lens element cooperates with a respective phosphorescent layer 36, the radius of curvature of the lens being chosen, in relationship with the thickness of screen 31, so that its corresponding deposit 36 is essentially in the focal plane of the lens.

The mural screens or tubes, in accordance with the invcmion, are normally located at a suitable height so that the axis perpendicular to the center of the screen approximates a position half way between the eyes of a sitting observer and of a standing observer. When the front glass surface 31 is thick with res t to the pitch of lenses, the height of the eyes of an observer with r to that of the center of the screen will tend to be critical. In order to permit an observer rn- 'c latitude in choosing his position of observation, it is recommended that the lcnticular surface be molded in the manner shown schematically in Figure 4.

Figure 4 shows, to greatly and with only a very few lens and pho clan cuts, the construction of a lcnticular nod to eliminate the black space effect of the discontinuous fluorescent deposit and at the an ob between the in this the optical xes of adjacent lenses is made slightly smat r than the distances separating the centers of ztz'ijacent fluorescent deposits. This difference in pitch is a very minute amount, and, although the centers of both the enticular surface and the phosphorescent screen coincide at the center 0 of the screen, there will he an incre. v.ng dist ncc bet. 'een the centers of corresponding lens and fluorescent eicments as one progresses toward the ex r of the screen. This variation in center positions indicated in Figure 4, wherein maximum differences Pi and MN are seen at the extremities of the screen. inasmuch as the pitch of the lenses is smaller than that of the fluorescent target elements, as one progresses above the center of the screen, the optical centers of the lens elements fall increasingly below the centers of their respective fluorescent elements, the converse, of course, being true as one progresses below the center of the screen. The result of this type of construction is that 1 observer will see an essentially undistorted picture, devoid of: black spaces, from any position between the normal standing and normal sitting views. it has been found that, for a screen one yard llgh, extreme difference PR (or MN) is about one eig th of the glass thickness 57 of screen such as 31.

As may be seen from the foregoing description of my invention, this method of constructii a mural television tube lends itself readily to the produwon of a very large viewing surface. The tube as described herein is especially applicable to home installations. Typical dimensions for such a tube would disclose a picture face having a cross-wise dimension of about 42 inches, a height of about 34 inches, and an overall tube thickness of less than 10 inches. These dimensions, however, are not meant to restrict my invention, for considerable latitude of dimensioning is present in the construction of similar tubes for home television receivers. Moreover by modifications in design of the tube, and by the incorporation of appropriate distribution and amplification circuits, the tube may present, in its ultimate form, a surface of suflicient area for the viewing thereof by very large audiences in both indoor and outdoor shows.

It may further be seen that for color television, or for greater definition by other dot interlace systems, the number of perforations along any given line of the viewing screen may be increased by as much as 150% in accordance with the required transmission standards. This invention therefore provides a viewing surface which is readily adaptable to the reception of color television, as well as to that of three dimensional television on mural screens of from half a square yard to hundreds of square yards in area.

Figs. 9A through 9D show a detail of construction which is particularly etfective for color television using three colors such as blue, red and green or for very high definition black and white. In television image analysis it is recognized that there is a critical relation between line width, the size of elemental picture portions and their position relative to the beam.

It is well known that the number of scanning lines will determine the amount of detail that can be presented on any given area of a picture. It may be found desirable to increase the definition of a picture by vertically relocating two out of each eight fields by half the distance of two lines, and horizontally relocating crosswise four out of each eight fields by half the distance normally separating two successive signals. This relocation at the receiver is synchronized with the relocation at the viewer and is obtained by various deflecting or dephasing means known to the art. Higher definition can be obtained in the above described tube by further dividing the screen area covered by a single aperture by two or by four and providing selective gating means for each division of said area.

Fig. 9C shows one elemental area within perimeter A B C D normally receiving one signal on each alternate field, the aperture location being shown at 110. Aperture 110 and its gating electrode 111 are shown in cross section in Fig. 9D. Fractional apertures 120,- 121, 122 and 123 are cut out of insulated layers of laminated material. The layers support perforated electrodes that surround each aperture and which are selectively connected to apertures similarly located within all areas situated, for example, vertically from the described elemental area. All controlling electrodes for apertures similarly located within each elemental area are connected to a variable voltage supply. At the moment when a gating pulse opens aperture 110 by means of voltage applied to electrode 111 the same gating pulse may be applied selectively to electrodes 112, 113, 114 or 115, or to any two or three or four, depending upon the result that may be desired. For higher linedefinition, in which field scanning is moved in cycles of four line locations, as compared to two locations in interlaced line scanning the two additional intermediate line locations are obtained by gating together the two horizontal ones out of four apertures in each elemental area. For dot and line interlace scanning, only one aperture out of four is open at any one time. The sequence in which apertures are gated as compared from one area to the next one may be changed, so that a more complex dot interlace may be permitted, and so as to avoid patterns or moire effects that often result from dot interlace of too short or too simple a sequence.

By using in each elemental area four or three phosphors of different colors or by using colored mosaic support for the phosphorescent screen, colored areas may be activated selectively in the same way and manner as shown in Figures 90 and 9D. For instance, in a four color television system, the areas of phosphors corresponding to apertures 120 and 121 could be respectively green and yellow, or green and green (in a 3 color) system, and apertures 122 and 123 could be respectively red and blue. In this manner, any system, whether it be field sequential, line sequential or dot sequential may be received with this tube, provided the connections between each of the controlling electrodes may be changed to suit the system which the tube may be called upon to' receive. Classical provisions for selectively changing the sequence by changing dot or line connections need not be described since they are within the knowledge of persons versed in the art of tube manufacturing and may be made outside the tube. For a conventional 3 color system, Figures 9A and 9B show the distribution of apertures in each elemental area, each string of electrodes being selectively disposed in front of areas of phosphor emitting the basic colors green, red and blue. The same remarks made in the case of a four aperture area apply in this system.

The mural screen constructions of Figs. 9A and 9B is arranged to give increased detail by having each element of phosphorescent targets 36, shown in Figs. 3 and 7 as served by the grids formed by control electrodes 32, 33 and actuated by a group of three controlled apertures as shown in Fig. 9B. A screen which may be plane or built in the manner of screen 31 is provided with dif-' ferent colored phosphors 101, 102 and 103 representing blue, red and green respectively. Perforated electrodes 104, and 106 control the perforated openings to the blue, red and green phosphors 101, 102 and 103, respectively. All 104 electrodes are cross connected as are also all 105 and 106 electrodes, requiring only three control lead wires for color control wires. Control electrodes 107 and 108 correspond to electrodes 32 and 33. Elements 109 are insulating spacers.

In operation the grid construction of control electrodes 107 and 108 permits the illumination of one elemental area as in the case of electrodes 32 and 33. By means of electrodes 104, 105 and 106 only the proper color is caused to phosphoresce. It will be seen that although all the red electrodes 105 may be opened by a charge only the one corresponding to the charge on the grid formed by electrodes 107 and 108 actually is effective. As noted above these smaller elements increase definition for both color and black and white.

While there has been described what is at present considered to be the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, intended in the appended claims to cover in generic terms all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A mural screen for the reproduction of intelligence comprising a transparent plate, luminescent material on one side of said plate, wall means forming a cavity on the same side of said plate as said luminescent material, an ionizable gas within said cavity, ionizing electrodes for maintaining said gas in a state of ionization, an apertured grid closely adjacent said luminescent material, control electrodes associated with and intersecting at the apertures of said grid, said apertures and intersections of said control electrodes corresponding to elemental picture portions of the screen, means to apply voltages to said control electrodes to control the passage of ions through said apertures to said material, a support means for holding said plate, said grid and said control electrode structure in fixed relationship, said plate having convex-elemental lenses andsaid luminescent material being arranged in discrete portions corresponding in arrangement to said elemental lenses.

2. The combination set forth in claim 1, the radius of curvature of the elemental lens being such that the corresponding luminescent portions lie in their respective focal planes.

3. The combination set forth in claim 2, the optical axes of adjacent elemental lenses being very slightly smaller than the distance separating parallel center lines through adjacent discrete portions of said luminescent material whereby black spaces on said screen are eliminated.

4. The combination set forth in claim 3, said control electrodes arranged to provide elemental picture areas on said screen disposed according to Cartesian coordinates.

5. The combination set forth in claim 1, said ionizing electrodes comprising an anode having relatively long and short conductive members and a plurality of cathode surfaces.

6. A substantially flat television tube, said tube being in the form of an oblong assembly comprising a transparent forward face and a complementary metallic rear surface, said forward face and said rear surface being sealed together around their respective peripheries to form a cavity within said sealed periphery, supporting means attached to the inner surface of said rear surface, a composite fluorescent viewing screen attached to said supporting means Within said cavity, said viewing screen having a transparent viewing face and a deposit of fluorescent material on the anterior surface of said viewing face, a plurality of horizontal and vertical conducting members disposed to form a cross-hatch network, means for obtaining a concentration of ions, said ions being disposed throughout said cavity behind said fluorescent screen, structural means supporting said cross hatch network for controlling a flow of said ions to said fluorescent means at predetermined intervals.

7. A substantially fiat television tube, said tube being in the form of an oblong assembly comprising a transparent forward face and a complementary metallic rear surface, said forward face and said rear surface being sealed together around their respective peripheries to form a cavity within said sealed periphery, supporting means attached to the inner surface of said oblong assembly, a composite fluorescent viewing screen attached to said supporting means within said cavity, said viewing screen having a transparent viewing face, a plurality of depressions disposed along the anterior surface of said viewing face, discontinuous deposits of diiferently colored fluorescent materials in said depressions, a plurality of horizontal conducting members electrically insulated from a plurality of vertical conducting members, said horizontal and vertical conducting members forming a cross-hatch configuration of total cross sectional area substantially equal to that of said viewing face, means for obtaining a concentration of ions in said cavity behind said fluorescent screen, structural means supporting said cross-hatch network in close proximity to said fluorescent deposit intermediate to said ions, and pulse distribution means electrically coupled to said cross hatch network for controlling a flow of said ions to said fluorescent material at predetermined intervals.

8. A television tube as claimed in claim 7 wherein said discontinuous deposit of fluorescent material is disposed in said corrugations in accordance with a desired configuration of line and dot elements.

9. The combination set forth in claim 8, the individual areas of said cross-hatch configuration being subdivided into elemental portions, supplemental control conductors for said elemental portions, said supplemental control conductors being connected to said pulse distribution means.

10. In combination, in a television tube having a light transmitting picture producing plate, portions of said plate having fluorescent material thereon producing one color and adjacent portions of said plate having fluorescent material thereon producing another color charged particle producing means, a charged particle control assembly mounted closely adjacent said plate and comprising a sheet of material carrying a grid composed of: two groups of insulated electrodes having crossing areas corresponding to picture producing elemental areas on said plate, said sheet being provided with a plurality of apertures at said crossing areas corresponding to elemental picture areas of at least two different color phosphors on said picture producing plate and serving as gates to control the action of charged particles on said picture producing plate.

ll. The combination set forth in claim 10, means for applying video signals to one of said groups of electrodes, said plate having three different colors of fluorescent material thereon and means for applying a voltage to said material sufliciently high to attract charged particles thereto.

12. The combination set forth in claim 11, said control means comprising means to apply control voltages to said groups of electrodes and to said material to modulate selectively the light produced by said material at each said elemental area.

13. in a color television tube a surface carrying different color phosphors, means for producing charged particles, a grid composed of two groups of insulated electrodes having crossing areas corresponding to picture producing elemental areas on said surface, each of said elemental areas having at least two phosphors of different colors therein, each said crossing areas containing apertures for the passage of charged particles to affect said phosphors, supplemental electrodes for controlling the passage of charged particles through said apertures, there being at least one supplemental electrode at each crossing area for each color of phosphor on the corresponding elemental picture producing area of said surface, all said supplemental electrodes for controlling the same color phosphor on said surface being connected together so as to require only a single control lead for each color and means to apply control voltages to said leads to the supplemental electrodes and to said groups of electrodes in proper sequence and modulated to produce the desired picture on said surface.

14. The combination set forth in claim 13, said means to apply control voltages comprising means to apply video signals to one of said groups of electrodes, suitable saw tooth charged particle attracting voltages to said phosphor and gating voltages to said supplemental electrode leads to control color.

References Cited in the file of this patent UNITED STATES PATENTS 2,091,152 Malplica Aug. 24, 1937 2,222,197 EngleS NOV. 19, 1940 2,254,057 Arni et al Aug. 26, 1941 2,313,286 Okolicsanyi Mar. 9, 1943 2,442,985 Rajchman June 8, 1948 2,513,743 Rajchman July 4, 1950 2,531,399 Cawein et al Nov. 28, 1950 2,558,019 Toulon June 26, 1951 2,567,656 Siezen Sept. 11, 1951 FOREIGN PATENTS 50,433 France June 5, 1940 356,760 Great Britain Sept. 11, 1931 

